[gdal-dev] gdal reading in grib values in awrong state?

[Brian Case]

Matt,

At a quick glance I would say pygrib is outputting in kelvin and gdal
Celsius. also it looks like there not in the same order.

Brian



On Thu, 2011-05-05 at 14:57 -0600, mafunk at nmsu.edu wrote:
> Hi,
> i am a little confused. I am using the gdal/python and trying to read
> values from a grib file (i can email the file if needed). I am using
> pygrib to compare against. I do this with the following code:
> 
> import struct
> 
> import pygrib
> 
> from osgeo import gdal
> from osgeo import ogr
> from osgeo import osr
> from osgeo import gdal_array
> from osgeo import gdalconst
> from osgeo.gdalconst import *
> 
> import numpy as np
> from numpy import *
> 
> #path = "../Data"
> #filename = "%s/ds.temp.bin" % (path)
> filename = "ds.temp.bin"
> 
> print "\n\nTesting with pygrib, opening file: %s\n" % (filename)
> grbs = pygrib.open(filename)
> rows = -1
> cols = -1
> grbs.seek(0)
> for grb in grbs:
>     print "grb:"
>     grb
>     print "grb.keys():"
>     print grb.keys()
>     for key in grb.keys():
>         print "\nKey: " + key
>         print "data:"
>         print grb[key]
> 
> 
> 
>     #print "grb['values']"
>     #print grb['values']
>     #print "grb['codedValues']"
>     #print grb['codedValues']
> 
>     (pg_lats,pg_lons) = grb.latlons()
>     pg_rows = pg_lats.shape[0]
>     pg_cols = pg_lats.shape[1]
>             #print test
>             #print lats.shape, lats.min(), lats.max(), lons.shape,
> lons.min(), lons.max()
>             #lat_pygrib_arr = []
>     print size(pg_lats)
> print "\n\n"
> 
> 
> ## open with gdal
> ds = gdal.Open(filename)
> band = ds.GetRasterBand(1)
> data = band.ReadAsArray(0,0,band.XSize,band.YSize)#.flatten()
> print "data:"
> print data
> 
> 
> The data values i get from pygrib are:
> data:
> [[ 294.5   294.5   294.5  ...,  298.31  298.32  298.32]
>  [ 294.5   294.5   294.5  ...,  298.32  298.22  298.22]
>  [ 294.4   294.4   294.4  ...,  298.22  298.22  298.22]
>  ...,
>  [ 280.91  280.91  280.81 ...,  264.2   264.3   264.5 ]
>  [ 280.81  280.81  280.81 ...,  263.5   263.7   263.9 ]
>  [ 280.81  280.81  280.81 ...,  262.8   263.    263.3 ]]
> 
> The values i get from gdal are:
> data:
> [[  7.65999756   7.65999756   7.65999756 ..., -10.35001221 -10.15
>    -9.85001221]
>  [  7.65999756   7.65999756   7.65999756 ...,  -9.65        -9.45001831
>    -9.2500061 ]
>  [  7.76000366   7.76000366   7.65999756 ...,  -8.95001831  -8.85001221
>    -8.65      ]
>  ...,
>  [ 21.2499939   21.2499939   21.2499939  ...,  25.07000122  25.07000122
>    25.07000122]
>  [ 21.35        21.35        21.35       ...,  25.17000732  25.07000122
>    25.07000122]
>  [ 21.35        21.35        21.35       ...,  25.15999756  25.17000732
>    25.17000732]]
> 
> Is there anything obvious that i am doing wrong?
> 
> thanks
> matt
> 
> 
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